This project seeks to advance our understanding of the precursors of early- and late-starting pathways of antisocial behavior (AB) by following a cohort of low-income, male youth form infancy through early adolescence. Using a model guided by a reciprocal and transactional perspective, our first aim is to test how child, parenting, and family factors in early childhood, in conjunction with child, parent, family, peer, and neighborhood factors in middle childhood and adolescence, lead to early-starting trajectories of antisocial outcomes during adolescence. We hypothesize that early child, parent, and family factors lead to coercive cycles of interaction that reinforce and coalesce patterns of child AB at school entry. During the school-age and adolescent periods, child, parent, and family factors continue to affect the course of AB; however, because of the child's increasing exposure to forces outside of the home, peer and neighborhood factors take on increasing importance in influencing trajectories toward serious forms of AB. A second goal is to examine predictors of late-starting trajectories of AB, which are believed to be moderately influenced by child, parenting, and family risk factors in early and middle childhood, and potentiated by youth's life events, and peer and neighborhood factors during adolescence. The model will be tested with a sample of 310 low-income, ethnically diverse boys who have been seen with their families on 10 occasions since infancy and will be evaluated again from ages 15 and 18 during the study period. This age period represents the apex of serious forms of antisocial behavior in the life course, when both early- and late-starting youth have been found to demonstrate high rates of delinquent activity. During the proposed funding period, target youth will be visited at their homes with their parents, siblings, best friends, and/or romantic partners at ages 15 and 17, and interviewed over the phone at ages 16 and 18. Additional reports of youth behavior will come from school, court, and police records.